The invention relates to an apparatus comprising:
An electric power supply device for supplying a voltage to the apparatus,
an electric power cut detecting circuit for detecting cuts of this supply voltage,
a memory fed by this electric power supply device,
a device for loading this memory,
a restarting device for initializing the apparatus.
The invention also relates to a method of starting and restarting apparatus subjected to supply voltage cuts.
The invention finds its application in portable telephones forming part of cellular radio telephone networks.
A problem posed with this type of apparatus is the unwanted switching-off due to electric power supply cuts of the apparatus. This occurs, for example, with a mechanical shock that causes the supply voltage to be cut off very briefly. After this very brief electric power cut, which must be detected, it is necessary to make sure that certain measures are taken after this detection. On this subject European patent document no. EP 0 607 919 may be consulted.
In this document the duration of the micro cut of supply voltage is measured by means of a counter which implies the presence of an auxiliary battery for supplying electric power during the power cuts and various measures are taken as a function of this duration.
The present invention proposes to make the resumption of the operation of the apparatus more certain after a very brief electric power cut, without the need for an auxiliary battery or too complex circuits.
For this purpose, such apparatus is characterized in that it further includes:
a control device for controlling the integrity of the memory to switch the restart device into service in the case where the integrity of said memory is lost.
If the apparatus were dead before the resumption of the electric power supply, it is no longer necessary to switch the restart device into service.
A start and restart method is characterized in that, when a very brief electric power cut has been detected, the integrity of said random-access memory is tested, while the restart process is simplified if the contents of the random-access memory have not been changed during the very brief electric power cut.
These and other aspects of the invention are apparent from and will be elucidated, by way of non-limitative example, with reference to the embodiment(s) described hereinafter.